1. Field of the Invention
The present invention relates to a method and a system for initiating communication with an implantable medical device to conduct a wireless communication session between the implantable medical device and an external (extracorporeal) programmer device.
2. Description of the Prior Art
When communicating with an implantable medical device (IMD) implanted in tissue of a human or animal body, a radio frequency (RF) transceiver is used for wireless communication of signals to/from RF communication circuitry comprised in the IMD. An IMD may be embodied in the form of an implantable cardioverter defibrillator (ICD), a neural simulator, an implantable drug pump, an implantable cardiac monitor or health monitor, a pacemaker, etc. Communication may be established with the IMD for a number of reasons. For instance, medical personnel may want to monitor and/or adjust parameters of the IMD, it may be desirable to perform medical or therapeutic treatment of the body via the IMD, e.g. defibrillation, restart of a stopped heart, injection of an insulin dose, etc. Needless to say, RF signalling enables establishment of a communication channel without having to open up the patient surgically. Hence, an RF device referred to as a programmer is employed to establish RF communication with transceiver circuitry within an IMD. From a user's point of view, a programmer may be viewed upon as a computer arranged with an RF transceiver, a user interface for controlling the programmer and dedicated software designed for the purpose of communicating with an IMD. When establishing communication with an IMD, the programmer broadcasts a wake-up signal to which the IMD responds before a communication session may be undertaken between the programmer and the IMD, i.e. before payload data is exchanged between the programmer and the IMD.
In certain environments, such as in hospitals or other care institutions, a situation may arise where a number of patients carrying IMDs are located within the coverage area (broadcast) of a programmer. When an operator uses the programmer to broadcast an RF wake-up signal for establishing communication with an IMD, it may happen that more than one IMD respond to the broadcast. This multi-device response to a broadcast is problematic for a number of reasons. For instance, a collision of responses may arise in uplink communication from the IMDs to the programmer. Potentially, the established communication channel may fail in case of uplink response collisions. International patent application having publication number WO 2006/014713 discloses a medical system and a method of establishing communication between a plurality of implantable medical devices and an external device by means of an identification command sent transcutaneously to the implantable medical devices. The implantable medical devices respond to the identification command with a response in one of a plurality of time slots. The external device receives the response from each of the implanted medical devices and establishes transcutaneous communication to a selected one of the devices based upon an order in time of which the implanted medical devices respond.
Even though the disclosure of WO 2006/014713 may mitigate problems relating to uplink response collisions, a problem still remains in that a selected response provides the external device with an IMD identifier, but a user of the external device still needs to determine which one of the plurality of physical IMDs located within the communication range of the external device that actually corresponds to the selected response.